1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
|
module Haddock.Backends.Hyperlinker.Parser
( parse
, Token(..), TokenType(..)
, Position(..), Span(..)
) where
import Data.Char
import Data.List
data Token = Token
{ tkType :: TokenType
, tkValue :: String
, tkSpan :: Span
}
data Position = Position
{ posRow :: !Int
, posCol :: !Int
}
data Span = Span
{ spStart :: Position
, spEnd :: Position
}
data TokenType
= TkIdentifier
| TkKeyword
| TkString
| TkChar
| TkNumber
| TkOperator
| TkGlyph
| TkSpecial
| TkSpace
| TkComment
| TkCpp
| TkUnknown
parse :: String -> [Token]
parse = tokenize . tag . chunk
chunk :: String -> [String]
chunk [] = []
chunk str@(c:_)
| isSpace c = chunk' $ span isSpace str
chunk str
| "--" `isPrefixOf` str = chunk' $ span (not . (== '\n')) str
| "{-" `isPrefixOf` str = chunk' $ chunkComment 0 str
| otherwise = chunk' $ head $ lex str
chunk' :: (String, String) -> [String]
chunk' (c, rest) = c:(chunk rest)
chunkComment :: Int -> String -> (String, String)
chunkComment _ [] = ("", "")
chunkComment depth ('{':'-':str) =
let (c, rest) = chunkComment (depth + 1) str
in ("{-" ++ c, rest)
chunkComment depth ('-':'}':str)
| depth == 1 = ("-}", str)
| otherwise =
let (c, rest) = chunkComment (depth - 1) str
in ("-}" ++ c, rest)
chunkComment depth (e:str) =
let (c, rest) = chunkComment depth str
in (e:c, rest)
tag :: [String] -> [(Span, String)]
tag =
reverse . snd . foldl aux (Position 1 1, [])
where
aux (pos, cs) c =
let pos' = move pos c
in (pos', ((Span pos pos', c):cs))
move pos str@(c:_)
| isSpace c = foldl move' pos str
move pos str = pos { posCol = posCol pos + length str }
move' pos '\n' = pos { posRow = posRow pos + 1, posCol = 1 }
move' pos _ = pos { posCol = posCol pos + 1 }
tokenize :: [(Span, String)] -> [Token]
tokenize =
map aux
where
aux (sp, str) = Token
{ tkType = classify str
, tkValue = str
, tkSpan = sp
}
classify :: String -> TokenType
classify (c:_)
| isSpace c = TkSpace
| isDigit c = TkNumber
| c `elem` special = TkSpecial
| c == '#' = TkCpp
| c == '"' = TkString
| c == '\'' = TkChar
classify str
| str `elem` keywords = TkKeyword
| str `elem` glyphs = TkGlyph
| all (`elem` symbols) str = TkOperator
| "--" `isPrefixOf` str = TkComment
| "{-" `isPrefixOf` str = TkComment
| isIdentifier str = TkIdentifier
| otherwise = TkUnknown
keywords :: [String]
keywords =
[ "as"
, "case"
, "class"
, "data"
, "default"
, "deriving"
, "do"
, "else"
, "hiding"
, "if"
, "import"
, "in"
, "infix"
, "infixl"
, "infixr"
, "instance"
, "let"
, "module"
, "newtype"
, "of"
, "qualified"
, "then"
, "type"
, "where"
, "forall"
, "mdo"
]
glyphs :: [String]
glyphs =
[ ".."
, ":"
, "::"
, "="
, "\\"
, "|"
, "<-"
, "->"
, "@"
, "~"
, "~#"
, "=>"
, "-"
, "!"
]
special :: [Char]
special = "()[]{},;`"
-- TODO: Add support for any Unicode symbol or punctuation.
-- source: http://stackoverflow.com/questions/10548170/what-characters-are-permitted-for-haskell-operators
symbols :: [Char]
symbols = "!#$%&*+./<=>?@\\^|-~:"
isIdentifier :: String -> Bool
isIdentifier (s:str)
| (isLower' s || isUpper s) && all isAlphaNum' str = True
where
isLower' c = isLower c || c == '_'
isAlphaNum' c = isAlphaNum c || c == '_' || c == '\''
isIdentifier _ = False
|
